The Wonders of Water
When You Need More
activity, heat, and humidity can increase our fluid needs. In these
situations, keep water bottles close at hand and drink frequently to avoid dehydration. If you're going to be physically active for
long periods, consider sports drinks that hydrate and provide easily usable
sugar and electrolytes.
Illnesses accompanied by increased body temperature, excessive perspiration,
vomiting, frequent urination, or diarrhea can also increase our fluid needs. Be sure to
drink plenty of liquids if you have one of these conditions, and see a doctor
if your fluid losses are excessive or prolonged.
How Much Is Too Much?
Scientists on the IOM panel did not set an upper limit for water.
"Water intoxication is very rare, although it has been seen in
fraternity pranks. That can be very serious and result in death" says David
Perlow, MD, an Atlanta-based urologist.
One recent study of Boston Marathon runners showed that one in three
marathon runners was drinking too much water during a race -- probably because
they were following recent advice to drink as much as tolerated.
If you follow your thirst, you won't go wrong, Perlow says. He notes that
pre-modern man never ran around sipping on a water bottle. A dry mouth
indicated it was time to run to the stream for a drink.
"Trust your thirst instinct to make sure you get enough fluids and, of
equal importance, void frequently," suggests Perlow.
Perlow says the bladder is like a balloon. When you make infrequent trips to
the bathroom, it can become overstretched -- which can result in problems with
incomplete emptying, he explains.
He recommends 7-12 trips to the toilet daily for most healthy people.
Water and Weight Control
For years, drinking water has been recommended for weight loss -- despite
the fact that fluids generally satisfy thirst and not hunger. Barbara Rolls, PhD, an expert on thirst and
satiety, points out that thirst and hunger are regulated by entirely different
A recent study by Rolls and colleagues at Penn State University looked at
whether people who drank water with lunch took in fewer calories than those who
drank other low-calorie beverages. They found that drinking water had little
effect on total calorie consumption at the meal.
"In all of our research, we have never been able to show that water can
cause weight loss," says Rolls. The only way drinking water can help you
lose weight is if you substitute it for higher-calorie beverages or foods, she
However, eating foods with high water content can help dieters, by
increasing the fullness factor.
"When you add water to a bowl of vegetables as in soup, the soup has
greater satiety than when the vegetables are eaten alone with a glass of
water," explains Rolls, author of The Volumetrics Eating Plan and The Volumetrics Weight
Control Plan. "When water is incorporated into food or shakes, satiety
is increased and subjects ultimately eat less food."
The weight loss benefits of water stem from several facts:
- Foods that incorporate water tend to look larger.
- The higher volume of these foods provides greater oral stimulation.
- Most important, when water is bound to food, it slows down absorption and
lasts longer in the belly.
If you want to lose weight, Rolls recommends an eating plan that includes
plenty of high-volume foods such as fruits, vegetables, broth-based soups, and
oatmeal, along with adequate fluids to satisfy your thirst.